Aerial firefighting commonly involves the operation of aircraft (A/C) in low altitude, high risk flight environments. Such flight environments may encompass fire-affected areas ranging from sparsely-populated or unpopulated regions of wilderness to densely-populated urban areas, such city environments in which A/C may be employed to combat structure fires in high-rise buildings. The flight environments may be characterized by elevated and shifting thermal gradients, dynamic wind conditions, and fire-induced updrafts. Visibility may be compromised by adverse weather conditions, time of day, and/or by the presence of large amounts of smoke, ash, and other airborne particulate matter. The airspace encompassing a fire-affected region may be occupied by other A/C, elevated terrain, man-made structures, and other obstacles. It is unsurprising, then, that aerial firefighting operations are often associated with high levels of risk. This is underscored by the fact that aviation-related accidents routinely account for a significant fraction of total firefighter fatalities on an annual basis. According to the National Institute for Occupational Safety and Health (NIOSH), the leading causes of fatal crashes during aerial firefighting operations include engine, structure, and component failure; pilot loss of control; failure to maintain adequate clearances from terrain, water, and obstacles; and hazardous weather conditions.
Enhanced Vision Systems (EVSs) offer the potential to reduce the number of accidents and fatalities occurring during aerial firefighting operations. Generally, an EVS is an aircraft-based system including at least one thermal image sensor, such as an infrared camera or millimeter wave radar sensor, which collects thermal image data external to the A/C during flight. The thermal image data collected by the EVS sensor is presented to the aircrew as an EVS image, which appears on a Head Up Display (HUD) or a Head Down Display (HDD) located in the A/C cockpit. In certain instances, the EVS image may be combined or blended with another database-dependent display to yield a composite display. For example, a Combined Vision System (CVS) display can be produced by integrating an EVS image into the Synthetic Vision System (SVS) image of a Synthetic Vision Primary Flight Display (SV-PFD). The larger database-dependent SVS image provides a contextual view exceeding the scope of the EVS image utilizing a stored terrain database, while the EVS image provides real-time, sensor-derived visual information more closely resembling the actual flight environment of the A/C. Such a CVS display and, specifically, the EVS image may thus serve as a useful, vision-enhancing tool during aerial firefighting operations in which visibility is often hindered.
While capable of improving pilot visibility during aerial firefighting operations, CVS displays and other avionic display incorporating EVS images are generally not adapted to address the unique challenges and mental tasks encountered by pilots in the context of aerial firefighting. There thus an exists an ongoing demand for avionic display systems, such as vision enhancing systems having augmented functionalities, which further improve situational awareness and aid pilot decision-making during aerial firefighting operations. Embodiments of such avionic display systems are described herein, as are methods for generating avionic displays including aerial firefighting symbology.